1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to protection film composition for a plasma display panel.
2. Background of the Related Art
Having all the advantages of the clear picture and the variety of screen sizes of cathode ray tubes, and the light and thin liquid display panel, the plasma display panel is considered as the next generation display. In general, the plasma display panel has a weight approx. ⅓ of the cathode ray tube of the same screen size, and a thickness below 10 cm even for a large sized panel of 40 to 60xe2x80x3. Moreover, though the cathode ray tube and the liquid crystal display have problems coming from a limitation on a size in displaying a digital data picture and a full motion on the same time, the plasma display panel has no such problems. And, while the cathode ray tube is influenced from a magnetic force, the plasma display panel is not influenced from the magnetic force, permitting to provide a stable picture to the watchers. And, since the pixels are controlled in a digital fashion, with no distortion of images at corners of the screen, the plasma display panel can provide a picture quality better than the cathode ray tube. The plasma display panel is provided with two glass substrates having electrodes coated thereon perpendicular, and opposite to each other. There are pixels at portions the electrodes are crossed. The operation of the plasma display panel is almost identical to the operation principle ofa domestic fluorescent lamp.
Referring to FIG. 1A, a related art triode surface discharge type plasma display panel has an upper substrate 10 and a lower substrate 20 bonded together to face each other. FIG. 1B illustrates a section of the plasma display panel shown in FIG. 1A, wherein a surface of the lower substrate 20 is rotated by 90xc2x0 for convenience of explanation. The upper substrate 10 has scan electrodes 16 and 16xe2x80x2 and sustain electrodes 17 and 17xe2x80x2 formed parallel to each other, a dielectric layer 11 coated on the scan electrodes 16 and 16xe2x80x2 and the sustain electrodes 17 and 17xe2x80x2, and a protection film 12. The lower substrate 20 has address electrodes 22, a dielectric film 21 on an entire surface of the substrate including the address electrodes 22, partition walls on the dielectric film 21 between the address electrodes 22, and a fluorescent material coating 24 on surfaces of the partition wall 23 and the dielectric film 21 in each discharge cell. A space between the upper and lower substrates 10 and 20 is filled with a mixture of inert gas, such as helium He and xenon Xe, to a pressure in a range of 400xcx9c500 Torr, to form a discharge space. In general, the inert gas filled in the discharge space of a D.C. plasma display panel is a mixture of helium and xenon (Hexe2x80x94Xe), and the inert gas filled in the discharge space of an A.C. plasma display panel is a mixture of neon and xenon (Nexe2x80x94Xe).
Referring to FIG. 2A and 2B, the scan electrodes 16 and 16xe2x80x2 and the sustain electrodes 17 and 17xe2x80x2 are provided with transparent electrodes 16 and 17 and bus electrodes 16xe2x80x2 and 17xe2x80x2 of a metal for enhancing light transmission of each discharge cell. FIG. 2A illustrates a plan view of the sustain electrode 17 and 17xe2x80x2 and the scan electrode 16 and 16xe2x80x2, and FIG. 2B illustrates a section of the sustain electrode 17 and 17xe2x80x2 and the scan electrode 16 and 16xe2x80x2. The bus electrodes 16xe2x80x2 and 17xe2x80x2 are provided with a discharge voltage from a driving IC fitted outside of the panel, and the transparent electrodes 16 and 17 are provided with the discharge voltage to the bus electrodes 16xe2x80x2 and 17xe2x80x2, to cause a discharge between adjacent transparent electrodes 16 and 17. The transparent electrode 16 and 17 has a total width of approx. 300 xcexcm of indium oxide or tin oxide, and the bus electrode 16xe2x80x2 and 17xe2x80x2 is a thin film having three layers of chrome-copper-chrome. A width of the bus electrode 16xe2x80x2 and 17xe2x80x2 line has approx. ⅓ of a width of the transparent electrode 16 and 17 line.
FIG. 3 illustrates wiring of the scan electrodes Smxe2x88x921, Sm, Sm+1, - - - , Snxe2x88x921, Sn, Sn+1 and the sustain electrodes Cmxe2x88x921, Cm, Cm+1, - - - , Cnxe2x88x921, Cn, Cn+1 arranged on the upper substrate, wherein, while the scan electrodes are discontinuous between each other, all the sustain electrodes are connected in parallel. In FIG. 3, the section enclosed by the dashed line represents an effective surface a picture is displayed thereon, and the other section represents a non-effective surface no picture is displayed thereon. The scan electrodes on the non-effective surface are in general called dummy electrodes 26, a number of which are not particularly limited.
The operation of the aforementioned triode surface discharge type A.C. plasma display panel will be explained with reference to FIGS. 4Axcx9c4D.
Referring to FIG. 4A, when a driving voltage is applied between the address electrode and the scan electrode, an opposed discharge is occurred between the address electrode and the scan electrode. The opposed discharge excites the inert gas in the discharge cell momentarily, to generate ions as the inert gas transits to a ground state, again. As shown in FIG. 4B, a portion of the ions, or atoms in quasi-excited states collide onto a surface of the protection film, which causes emission of secondary electrons from the surface of the protection film. The secondary electrons collide with the gas in a plasma state, to spread the discharge. As shown in FIG. 4C, when the opposed discharge between the address electrode and the scan electrode ends, wall charges with opposite polarities are generated on surfaces of the protection film over the sustain electrode and the scan electrode, respectively. And, as shown in FIG. 4D, when the driving voltage provided to the address electrode is cut off during the wall charges with opposite polarities build up at the scan electrode and the sustain electrode continuously, there is a surface discharge occurred in a discharge region on a surface of the dielectric layer and the protection layer due to a potential difference between the scan electrode and the sustain electrode. These opposed discharge and the surface discharge cause electrons in the discharge cell to collide onto the inert gas in the discharge cell, to generate an UV ray of 147 nm wavelength in the discharge cell as the inert gas is excited. The UV ray collide onto the fluorescent material coated on the address electrode and the partition wall, to excite the fluorescent material, which generates a visible light, that permits to implement a picture on the screen.
In order to make the plasma display panel to have a high commercial preference as a wall mounting type large sized display in view of technology, the plasma display panel should have a luminance and a lifetime, not inferior to the CRT. Particularly, the AC type plasma display panel is provided with a magnesium oxide MgO thin film for preventing damage to the dielectric layer and emitting the secondary electrons that drops the discharge voltage. In general, though the magnesium oxide is deposited on the dielectric layer by PVD, the PVD has a slow rate and costs high. Other than the PVD, there are a few methods for forming the magnesium oxide thin film in the plasma display panel, such as a method disclosed in the Society of Japanese Television IDY94-14, PP1-6, wherein formation of the protection film by screen printing a paste including magnesium oxide powder is suggested. However, the magnesium oxide protection film formed by this method has problems in that application to a front panel is not possible because the protection film is not transparent, and the pin holes formed in the protection film during coating shortens a lifetime. In order to prevent the formation of the pin holes in a thick film coating of the magnesium oxide, there is a method disclosed in Japanese Laid Open Patent Nos. H7-147136, and H8-77933, in which use of a mixture of magnesium oxide powder and a binder which is converted into magnesium oxide by baking, such as magnesium ethoxide, magnesium methoxide, magnesium n-propoxide, magnesium n-butoxide, magnesium methoxypropylate and the like is suggested. The foregoing method using a binder in a mixture has problems in that the magnesium alkoixde susceptible to moist deteriorates solution stability, and the great grain size of the magnesium oxide powder impedes formation of a transparent protection film. Other than the above method, Japanese Laid Open Patent No. H8-329844 discloses a method in which magnesium methoxide is dissolved in ethanol amine and added with a solvent, such as ethylene glycol, to form a coating composition, the coating composition is coated and baked, to form the magnesium oxide protection film. However, the magnesium oxide protection film obtained thus has problems of protection film damage and short lifetime caused by crack coming from separation of organic ligand, with a subsequent reduction of mass and contraction of the thin film.
Accordingly, the present invention is directed to protection film composition for a plasma display panel that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide protection film composition for a plasma display panel, which can form a magnesium oxide protection film which is transparent, has a high strength and a high bonding force, and forms no pin hole or crack.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the protection film composition for a plasma display panel consisting of a metal oxide including 60 wt %xcx9c90 wt % of magnesium 2-methoxyethoxide, and 10 wt %xcx9c40 wt % of metal polyoxohydroxide which may be expressed in a general formula MxOy(OH)2xxe2x88x922y(where x is xe2x80x981xe2x80x99, and y is xe2x80x980xe2x80x99 or xe2x80x981xe2x80x99), and an organic solvent.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.